For example, when a vehicle moves to an adjacent travel lane on a road where plural travel lanes are present (lane change), or when the vehicle turns right or left at an intersection to change a route (turn), it is necessary to give a turn indication signal so that a driver of another vehicle can recognize the lane change or the turn.
In order to give such a turn indication signal, turn signal lamps are provided as turn indicators (blinkers) in the vehicle. Further, as a driver operates an operation lever provided in the vicinity of a steering wheel of the vehicle, the turn signal lamp provided on a right side or a left side of a vehicle body can blink.
In the case of the lane change, before changing the lane, it is necessary that the turn signal lamp blinks for several seconds so that the driver of another vehicle can recognize the lane change. Further, in the case of the turn, it is necessary that blinking of the turn signal lamp be maintained until the turn is terminated.
In a general vehicle, an operation lever for switching an operation of a turn indicator has two-stage operation positions. For example, when a driver applies a force to the operation lever to slightly tilt the lever (first-stage position), a turn signal lamp blinks while the force is being applied to retain the lever. That is, if the force applied to retain the lever is released, the lever returns to a predetermined neutral position by a force of a spring, so that the blinking of the turn signal lamp is terminated. On the other hand, when the driver applies a force to the lever to greatly tilt the lever (second-stage position), the position of the lever is mechanically retained, and even though the driver releases the force applied to the lever, the turn signal lamp maintains the blinking state. Further, a mechanism for mechanically detecting a steering state of a steering wheel is provided, and when the steering is terminated, the retention of the operation lever is automatically released.
Accordingly, in normal driving, in the case of the lane change, the driver uses the first-stage position of the operation lever, and in the case of the right turn or the left turn, the driver uses the second-stage position of the operation lever. By using the second-stage position, when the right turn or the left turn based on the rotation of the steering wheel is being performed, it is not necessary to continuously apply the force for retaining the operation lever, and thus, the driving operation becomes comfortable. Further, in the right turn or left turn, if the turn is terminated, since the state is mechanically detected so that the operation lever automatically returns to the neutral position, the driver does not need to perform a special operation for terminating the blinking of the turn signal lamp.
As such a device that controls blinking of the turn signal lamp, an electronic control device that employs a sensor for detecting a steering angle is known, as disclosed in PTL 1 to PTL 3, for example.
PTL 1 discloses the following technique. An automatic return lever switch and a steering angle sensor for detecting a rotation direction and an angle of a steering wheel are connected to control means, and the control means outputs a predetermined turning signal based on an operation signal of the lever switch. Further, a turn signal lamp blinks by the turning signal, and a rotation position of steering is detected by the steering angle sensor. Further, during straightforward travelling, the output of the turning signal is stopped, and the turn signal lamp is turned off
PTL 2 discloses a technique for automatically turning off a turn signal at a suitable timing in a lane change. Specifically, a yaw rate sensor and a steering angle sensor are mounted, and when an initial velocity is in a high speed range, determination of a turning-off condition is performed based on a yaw rate detection signal with high reliability of a detection result during high speed traveling, and when the initial velocity is in a low speed range, the determination the turning-off condition is performed based on a steering angle detection signal with high reliability of a detection result during low speed traveling.
PTL 3 discloses a technique for preventing erroneous turning-off of a turn signal during right or left turn. Specifically, a turning-off condition is switched by automatically distinguishing right or left turn from lane change based on whether a steering angle of a steering angle sensor reaches a cancel preparation angle.
Further, PTL 4 discloses a conventional technique relating to a power steering device of a vehicle, which has no relation to blinking of a turn signal lamp. PTL 4 uses a steering angle detected by a steering angle sensor and a vehicle velocity detected by a vehicle speed sensor. Specifically, it is determined whether a steering wheel is in a turn increase state or in a return state from the detected steering angle. Further, a steering reaction force instruction value having a hysteresis characteristic is calculated with respect to the steering angle based on the steering angle and the vehicle speed, and an actuator such as a motor is drive-controlled so that a steering reaction force corresponding to the steering reaction force instruction value acts on the steering wheel.